though i am new to Knime, i thought to solve this easy problem by myself, but …
I hope you can help me.

At the end of a workflow i have the Group by Node with 2 Rows and 2 columns.
column 1 is a string with a name. column 2 is an integer.
so i have an absolute number for each column.

But i want to have a bar chart, not showing me absolut numbers.
if row one has 200 in its integer-column, and row 2 has 50, i want a bar chart that shows me 80% and 20%.

Bar charts are not commonly pre-set to show absolutes as percentages. I would use group by to sum the numbers, then append the total back as a new column, then the missing values node to copy the sum down, then divide to get your percentages, and feed that into the graph.

thank you for answer. i found other solution.
i changed to pie/donut chart instead of Bar Chart.
In Pie/donut i have “General Plot Options” and can use “labe type” “percent”.